1. Field of the Invention
The present invention relates to a data recording apparatus and a data recording method for data recording on a packet basis onto a track of an optical recording medium as well as to an optical recording medium having a track on which data is recorded on a packet basis.
2. Description of the Related Art
In an optical disc such as a compact disc (CD), data recording is performed through small holes, called pits, formed on a recording surface of the disc. Data is reproduced by reading presence/absence of the pit and its length. As the disc of such CD-specification, there are also a CD-Recordable (CD-R) disc in which additional data can be written and a CD-Rewritable (CD-RW) disc in which data can be rewritten.
Data recording to the CD-R and the CD-RW is usually performed as data recording on a logical track basis defined by the CD specification. However, since the maximum number of write tracks to be written is limited to 99, there is a problem that it is impossible to sufficiently utilize the storage capacity of the optical disc.
More specifically, such a recordable optical disc has: a program area for recording up to 99 data items on a logic track base of an arbitrary size; a TOC (table of contents) for recording contents information of the tracks recorded in this program area; and a PMA (program memory area) for temporarily recording information required for recording data on the program area.
When a data item is recorded on a logical track, the logical track number containing this data and the information on the recording start and end positions on the logical track are recorded in the PMA. Moreover, when a new data item is recorded starting at the end position of the logical track, the track position information recorded in the PMA is read out, so that a new data item is recorded starting at the end position of the logical track and this logical track position information is recorded on the PMA.
However, in this optical disc, when the program area contains 99 logical tracks recorded, a new data item cannot be recorded even when an area available for recording is remaining in this program area. Thus, the optical disc has a problem that it is impossible to use the storage capacity sufficiently.
To solve this problem, a so-called packet write has been suggested as the recording method. This packet write method is based on the CD specification but data recording is performed in a further smaller packet basis than the conventional track. For a single logical track, it is possible to constitute a plurality of packets. That is, in this optical disc, by recording data on packet basis on the logical track, it becomes possible to record data exceeding 99 logical tracks. Thus, even in an optical disc based on the CD specification, it is possible to fully utilize its recording capacity.
In the optical disc, information indicating the logical track position is recorded in the PMA but no information indicating the packet position is recorded. When writing an additional data by the packet write, it is necessary to retrieve the logical track from the head to the trail so as to find a packet end position of the packet containing logical track data, i.e., an NWA (next writable address) where a new data of the logical track can be recorded.
Conventionally, to find this NWA, as has been described above, the logical track is successively retrieved from the head to the end or the recording state of the intermediate position of the logical track is repeatedly retrieved to define the range.
However, in the optical disc, as the recording area of the logical track to be retrieved is increased, the time required for finding this logical track NWA is also increased. For this, in the optical disc, when recording data on a packet basis on the logical track, the recording speed is lowered.
By the way, in the optical recording apparatus for recording/reproducing a rewritable optical disc has a so-called blank function for erasing data over the entire optical disc surface and a so-called minimally blank function for erasing only the contents information of the track having the optical disc data recorded, so that data is pseudo-erased.
According to this minimally blank function, it is possible to pseudo-erase data recorded in the program area by erasing the data recorded in the PMA as the contents information, the data recorded in the read-in area and the read-out area, and the data recorded in the track pre-gap. Thus, it is possible to erase data recorded on an optical disc with a minimum time.
However, in the optical disc having the aforementioned logical track on which data has been recorded on packet basis, if an additional data is recorded by the packet write after a pseudo-erase of data with respect to the logical track, in the area where the logical track data has been pseudo-erased, data existing prior to the pseudo-erase is actually recorded. Accordingly, there is often a case that a data is written at an erroneous position, considering that the pseudo-erased data is an actual data. That is, in this optical disc, the contents information of the logical track containing data is erased but the actual data still remains and no information indicating the packet position is recorded. Accordingly, when retrieving the aforementioned NWA, data may be recorded starting at an erroneous position by considering that the pseudo-erase data is an actual data.